This product involves the detection and identification of DOPA metabolites and other reducing compounds in the urine of patients with malignant melanoma. Samples are analyzed by both cation- and anion-exchange chromatography to display the entire range of DOPA metabolites, from the aromatic acids (e.g., HVA), and amino acids (e.g., MOPA), to the catecholamines (e.g., DOPAmine). Detection is achieved via post-column colorimetric detection with diphenylpicrylhydrazyl (DPPH), with a passive detector, such as native fluorescence, often used simultaneously to assist in resolving overlapping DPPH peaks. Analysis of urines from fifty patients with widespread metastatic disease has shown that their patterns of DOPA metabolies bear no resemblance to the "normal" metabolism of DOPA, which is characterized largely by decarboxylation, and by excretion of catecholamines and their metabolites. In metastatic melanoma, the excretion of DOPAquinone metabolites, and the metabolites of non-decarboxylated DOPA predominate. In addition, several reducing metabolites that are neither pigment-related, nor polyamines, nor odd (t-RNA derived) nucleosides correlate strongly with disease.